Liquid fuel injection pumps for internal combustion engines



NOW 1967 K. A. w. KEMP 3,351,020

LIQUID FUEL INJECTION PUMPS FOR INTERNAL COMBUSTION ENGINES Filed Jan.19, 1966 United States Patent 6 LIQUID FUEL INJECTION PUMPS FOR INTERNALCOMBUSTION ENGINES Kenneth Albert Walters Kemp, London, England,assignor to C.A.V. Limited, London, England Filed Jan. 19, 1966, Bar.No. 521,621 Claims priority, application Great Britain, Jan. 29, 1965,2,439/65 7 Claims. (Cl. 103-2) ABSTRACT OF THE DISCLOSURE A fuelinjection pump of the rotary distributor type and incorporating a pairof pumping plungers and a chamber to receive a portion of the totalvolume of fuel pumped by the pumping plungers at the start of thepumping stroke. The chamber incorporating a movable piston which ismoved to its return position at the end of the injection stroke thedisplaced fuel being allowed to flow to a drain.

In the specification of my British Patent No. 950,063 there is describedand claimed a liquid fuel injection pump comprising a body part, arotary distributor within the body part, a head at one end of thedistributor and rotatable therewith, said head having formed therein aradial bore, a plunger in the bore, an annular cam surrounding the headfor actuating the plunger as the head rotates, a longitudinal passage inthe distributor in communication with said bore, a plurality ofannularly spaced ports in the body part adapted for connection to thecylinders of the engine respectively, a radial passage in thedistributor in communication with the longitudinal passage, said radialpassage being arranged to communicate with each in turn of said ports asthe distributor rotates, and during the time when the plunger is movedinwardly by the cam,

means for supplying fuel from a feed pump to the longitudinal passage inthe distributor whilst said radial passage is removed from the ports, acylinder formed in the body part, a shuttle occupying the cylinder andpermitted limited axial movement therein, a plurality of radial passagesin the distributor in communication with the longitudinal passage andadapted to communicate in turn with one end of said cylinder as thedistributor rotates and during the time when the plunger is movedinwardly by the cam, and means for supplying fuel to the opposite end ofthe cylinder under the control of a valve responsive to feed pumppressure.

With thistype of pump it is arranged that said one end of the cylinderremains in communication with one of the plurality of radial passagesfor a short time whilst the plunger is able to move outwardly so thatfuel contained in said one end of the cylinder can be discharged backinto the longitudinal passage, and in this manner the shuttle isreturned to its correct position before the plunger is again movedinwardly by the cam. It will be seen that one end of the cylinder has toremain in communication with each in turn of the plurality of radialpassages for an extended period and this leads to difiiculty when thepump is intended to supply fuel to an engine having more than fourcylinders.

The object of the present invention is to provide a pump generally ofthe kind just described in a simple and convenient form.

According to the invention a liquid fuel injection pump for supplyingfuel to an internal combustion engine having a plurality of cylinderscomprises in combination, a body part, a rotary distributor mounted inthe body part and arranged to be driven in timed relationship to anengine with which the pump is associated, a bore formed in thedistributor, a plunger slidable in said bore, a first passage formed inthe distributor in communication with said bore, a plurality ofoutwardly extending angularly spaced inlet passages formed in thedistributor in communication with said first passage, a fuel inlet portformed in the body part and with which said inlet passages register inturn as the distributor rotates, said inlet port communicating with asource of fuel under pressure so that as an inlet passage communicatestherewith fuel will flow to said bore to move the plunger outwardly, anoutwardly extending delivery passage formed in the distributor incommunication with said first passage, a plurality of angularly spacedoutlet ports formed in the body part and with which the delivery passagecan register in turn as the distributor rotates and during the time Whenthe inlet port is out of register with an inlet passage, a cam forimparting inward movement to the plunger during the time when thedelivery passage is in register with an outlet port, a cylinder formedin the body part, a shuttle slidable in said cylinder, a stop forlimiting the movement of the shuttle away from one end of the cylinder,means urging the shuttle towards said one end of the cylinder, a spillport in communication with said one end of the cylinder, said spill portbeing positioned so that the inlet passages in turn, can registertherewith as the distributor rotates and during the time when theplunger is being moved inwardly by the cam, and further ways in thedistributor through which the spill port can communicate with a drainduring the time when the spill port is not in communication with aninlet passage.

In the accompanying drawings:

FIGURE 1 is a sectional side elevation of one example of a pump inaccordance with the invention for supplying fuel to a four cylinderengine;

FIGURE 2 is a section on the line 22 of FIGURE 1; and

FIGURE 3 is a view of part of the pump shown in FIG URE 1 in a modifiedform.

Referring to the drawings there is provided a body part 10 in which ismounted a rotary distributor 11, the latter being adapted to be drivenin timed relationship with the engine. At one end of the distributor aremounted the,

rotary parts of a vane type feed pump 12 having an inlet 13 and anoutlet 14 defined in the body part. The inlet is, in use, connected to asource of fuel and is also connected to the outlet through a reliefvalve 15 which regulates the fuel pressure at the outlet. At the otherend of the distributor is formed a transverse, bore 16 in which aremounted a pair of plungers 17 and these are arranged to be movedinwardly, as the distributor rotates, by four equi-angularly spaced camlobes formed on an annular cam ring 18, rollers 19 being mountedintermediate the cam ring and the plungers respectively. Formed in thedistributor is a longitudinal passage 20 which communicates with thetransverse bore 16 and which at one point has extending therefrom adelivery passage 21. The latter communicates, in turn, as thedistributor rotates and whilst the plungers 17 are being moved inwardlyby the cam livery passage 21 is out of register with the outlet ports22.,

The inlet port is in communication with the outlet 14 of the feed pumpand there is provided an adjustable throttle lalve 24a for controllingthe quantity of fuel flowing to :he inlet port. The pump so fardescribed operates in a Well known way. Fuel is passed to the transversebore 16 move the plungers 17 outwardly whilst the inlet port 24 is inregister with one of the inlet passages 23 and as the distributorfurther rotates the plungers are moved inwardly and fuel is dischargedfrom the transverse bore and flows via the delivery passage 21 and oneof the outlet ports 22 to a combustion space of the engine.

Further provided in the body part is a cylinder 25 one end of which isin communication with a spill port 26 which is located so as toregister, in turn, with the aforesaid inlet passages 23 during the timewhen the plungers 17 are being moved inwardly. Within the cylinder is aslidable shuttle 27 and this is loaded towards said one end of thecylinder by fuel pressure, derived from the outlet'14 of the feed pumpby way of a circumferential groove 28 on the distributor, acting on theremote end of the shuttle. Moreover, an adjustable stop 29 is providedto limit the movement of the shuttle 27 away from said one end of thecylinder.

Formed in the distributor are further ways which take the form of fouraxially extending grooves 30 which are alternately disposed with theinlet passages 23 and which communicate in turn with the spill port 26during the time when the inlet port 24 is in communication with an inletpassage 23. Furthermore, during the time when a particular groove 30 isin register with the spill port 26 the groove also communicates with aspill passage 31 formed in the body part, the latter being connected tothe inlet of the feed pump.

In use when the plungers 17 are moved inwardly by the cam lobes fuelwill flow into said one end of the cylinder 25 and will move the shuttle27 until the latter contacts the stop 29 whereafter the remainingquantity of fuel displaced from the transverse bore 16 will flow throughthe delivery passage to one of the outlet ports and from there to acombustion space of the engine. When the distributor further rotates thespill port communicates with one of the axially extending grooves 30 andfuel contained in said one end of the cylinder will be displaced by theshuttle to the inlet of the feed pump thereby allowing the shuttle toassume its initial position ready for the next cycle.

By this means the maximum quantity of fuel which can be delivered to theengine is controlled in an extremely convenient manner, and thisquantity can be adjusted by altering the settingof the stop 29. Ifdesired and as shown in FIGURE 3 the shuttle may be loaded towards saidone end of the cylinder by resilient means in the form of a coiledspring 32.

In order to control the torque or power output of the engine a valve isprovided to control the rate at which fuel can escape through the spillport. By this means the return motion of the shuttle 27 towards said oneend of the cylinder 25 is impeded. If the shuttle does not move themaximum extent permitted then when the plungers 17 are next movedinwardly less fuel will be required to move the shuttle to contact thestop 29 with the result that more fuel will be delivered to the engine.The setting of the valve is arranged to be dependent upon the speed ofthe engine and the valve is arranged so that as the speed of rotation ofthe engine increases the rate at which fuel can flow through the spillport is decreased.

As shown in FIGURE 1 of the drawings the valve takes the form of acylindrical valve member 33 which is mounted within a bore disposed sothat the spill passage 31 intersects same. The valve member is loadedtowards one end of the bore by a coiled compression spring 34accommodating within a hollow cap 35 secured to the body part. Said oneend of the bore is in communication with the outlet 14 of the feed pumpso that outlet pressure of the feed pump which varies in accordance withthe speed of the engine, acts to move the valve member against theaction of the spring. Intermediate its ends the valve member is formedto truncated conical shape and the arrangement is such that as the speedof the engine increases the valve member is moved to restrict thepassage 31 so that the rate at which fuel can flow through the spillport 26 is reduced.

For starting purposes when an excess of fuel is required, a manuallyoperable valve which may be located in the spill passage 3-1 or in thepassage connecting groove 28 to the said other end of the cylinder 25 ofthe example shown in FIGURE 1 is provided. The valve is operable fromthe extension of the pump to prevent the flow of fuel through thepassages. The effect of closing the passages is to prevent the shuttle27 moving outwardly or if it does move outwardly, to prevent itreturning and in either case no fuel will be spilled during the inwardmovement of the plungers so that an excess of fuel will be supplied tothe engine.

Having thus described my invention what I claim as new and desire tosecure by Letters Patent is:

1. A liquid fuel injection pump for supplying fuel to an internalcombustion engine having a plurality of cylinders comprises incombination, a body part, a rotary distributor mounted in the body partand arranged to be driven in timed relationship to an engine with whichthe pump is associated, a bore formed in the distributor, a plungerslidable in said bore, a first passage formed in the distributor incommunication with said bore, a plurality of outwardly extendingangularly spaced inlet passages formed in the distributor incommunication with said first passage, a fuel inlet port formed in thebody part and with which said inlet passages register in turn as thedistributor rotates, said inlet port communicating with a source of fuelunder pressure so that as an inlet passage communicates therewith fuelwill flow to said bore to move the plunger outwardly, an outwardlyextending delivery passage formed in the distributor in communicationwith said first passage, a plurality of angularly spaced Outlet portsformed in the body part and with which the delivery passage canregister, in turn as the distributor rotates and during the time whenthe inlet port is out of register with an inlet passage, a cam forimparting inward movement to the plunger during the time when thedelivery passage is in register with an outlet port, a cylinder formedin the body part, a shuttle slidable in said cylinder, a stop forlimiting the movement of the shuttle away from one end of the cylinder,means urging the shuttle towards said one end of the cylinder, a spillport in communication with said one end of the cylinder, said spill portbeing positioned so that the inlet passages in turn, can registertherewith as the distributor rotates and during the time when theplunger is being moved inwardly by the cam, a valve for controlling theflow of fuel through the spill port, the setting of which is dependentupon the speed at which the distributor is driven, and further ways inthe distributor through which the spill port can communicate with adrain during the time when the spill port is not in communication withan inlet passage.

2. A liquid fuel injection pump as claimed in claim 1 in which theshuttle is urged towards said one end of the cylinder by fuel underpressure derived from said source.

3. A liquid fuel pump as claimed in claim 1 includinga spring for urgingsaid shuttle towards said one end of the cylinder.

4. A liquid fuel pump as claimed in claim 1 including means for impedingthe return motion of the shuttle towards said one end of the cylinder.

5. A liquid fuel pump as claimed in claim 1, in which the motion of theshuttle away from said one end of the bore can be prevented to enable anexcess of fuel to be supplied by the pump.

6. A liquid fuel injection pump as claimed in claim 1 includingvalve-means for controlling the output pressure of said source so thatthe pressure varies in accordance with the speed at which the pump isdriven, the valve which controls the flow of fuel through the spill portbeing a pressure responsive valve actuated by the outlet pressure ofsaid source.

7. A liquid fuel injection pump as claimed in claim 6 in which saidvalve comprises a valve member which is movable Within a bore whichintersects a passage through Which fuel flows from said spill port, saidvalve member being urged by a spring towards one end of said bore andbeing moved against the action of the spring by the pressure of fueldelivered by said source, said valve member being shaped so as to definea restriction to the flow of fuel through the passage, the restrictionimposed being varied as the valve member is moved.

References Cited UNITED STATES PATENTS 10/1962 Evans 103-41 10/1962Bessiere 103--5 2/1965 Bessiere 10 3-42 7/1965 Kemp 103-2 12/ 1966 Evans1032 FOREIGN PATENTS 11/ 1964 France.

2/ 1964- Great Britain.

DONLEY J. STOCKING, Primary Examiner. 15 W. J. KRAUSS, AssistantExaminer.

1. A LIQUID FUEL INJECTION PUMP FOR SUPPLYING FUEL TO AN INTERNALCOMBUSTION HAVING A PLURALITY OF CYLINDERS COMPRISES IN COMBINATION, ABODY PART, A ROTARY DISTRIBUTOR MOUNTED IN THE BODY PART AND ARRANGED TOBE DRIVEN IN TIMED RELATIONSHIP TO AN ENGINE WITH WHICH THE PUMP ISASSOCIATED, A BORE FORMED IN THE DISTRIBUTOR, A PLUNGER SLIDABLE IN SAIDCORE, A FIRST PASSAGE FORMED IN THE DISTRIBUTOR IN COMMUNICATION WITHSAID BORE, A PLURALITY OF OUTWARDLY EXTENDING ANGULARLY SPACED INLETPASSAGES FORMED IN THE DISTRIBUTOR IN COMMUNICATION WITH SAID FIRSTPASSAGE, A FUEL INLET PORT FORMED IN THE BODY PART AND WITH WHICH SAIDINLET PASSAGES REGISTER IN TURN AS THE DISTRIBUTOR ROTATES, SAID INLETPORT COMMUNICATING WITH A SOURCE OF FUEL UNDER PRESSURE SO THAT AS ANINLET PASSAGE COMMUNICATES THEREWITH FUEL WILL FLOW TO SAID BORE TO MOVETHE PLUNGER OUTWARDLY, AN OUTWARDLY EXTENDING DELIVERY PASSAGE FORMED INTHE DISTRIBUTOR IN COMMUNICATION WITH SAID FIRST PASSAGE, A PLURALITY OFANGULARLY SPACED OUTLET PORTS FORMED IN THE BODY PART AND WITH WHICH THEDELIVERY PASSAGE CAN REGISTER, IN TURN AS THE DISTRIBUTOR ROTATES ANDDURING THE TIME WHEN THE INLET PORT IS OUT OF REGISTER WITH INLETPASSAGE, A CAM FOR IMPARTING INWARD MOVEMENT TO THE PLUNGER DURING THETIME WHEN THE DELIVERY PASSAGE IS IN REGISTER WITH AN OUTLET PORT, ACYLINDER FORMED IN THE BODY PART, A SHUTTLE SLIDABLE IN SAID CYLINDER, ASTOP FOR LIMITING THE MOVEMENT OF THE SHUTTLE AWAY FROM ONE END OF THECYLINDER, MEANS URGING THE SHUTTLE TOWARDS SAID ONE END OF THE CYLINDER,A SPILL PORT IN COMMUNICATION WITH SAID ONE END OF THE CYLINDER, SAIDSPILL PORT BEING POSITIONED SO THAT THE INLET PASSAGES IN TURN, CANREGISTER THEREWITH AS THE DISTRIBUTOR ROTATES AND DURING THE TIME WHENTHE PLUNGER IS BEING MOVED INWARDLY BY THE CAM, A VALVE FOR CONTROLLINGTHE FLOW OF FUEL THROUGH THE SPILL PORT, THE SETTING OF WHICH ISDEPENDENT UPON THE SPEED AT WHICH THE DISTRIBUTOR IS DRIVEN, AND FURTHERWAYS IN THE DISTRIBUTOR THROUGH WHICH THE SPILL PORT CAN COMMUNICATEDWITH A DRAIN DURING THE TIME WHEN THE SPILL PORT IS NOT COMMUNICATIONWITH AN INLET PASSAGE.